-LRB- CNN -RRB- An Ohio man who authorities accuse of plotting to attack the U.S. Capitol appeared in a Cincinnati court Thursday and entered a plea of not guilty .

Christopher Lee Cornell , 20 , has been charged with attempting to kill government employees , solicitation to commit a crime and possession of a firearm .

The first two charges are punishable by up to 20 years in prison , while the third charge can carry a possible sentence of up to five years behind bars .

Authorities say Cornell planned to set off bombs at the U.S. Capitol and then open fire on people as they fled .

He came to the FBI 's attention several months ago after posting about his support for violent jihad on social media , according to a criminal complaint .

The FBI launched an undercover operation , with the help of a person who began cooperating in exchange for favorable treatment on his criminal exposure on an unrelated case .

Cornell allegedly told that source he had been in contact with persons overseas , and that he had aligned himself with ISIS .

He did not think he would receive `` specific authorization to conduct a terrorist attack in the United States , but stated that he wanted to go forward with violent jihad and opined that this would be their way of supporting ISIL , '' the complaint said , using another name for ISIS .

According to the complaint , Cornell wrote : `` I believe that we should just wage jihad under our own orders and plan attacks and everything . I believe we should meet up and make our own group in alliance with the Islamic State here and plan operations ourselves . ''

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Christopher Lee Cornell , 20 , is charged with attempting to kill government employees

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Authorities say he planned to set off bombs at the U.S. Capitol and then open fire on people as they fled